JP2003082584A - Chemical modification of polyimide - Google Patents

Abstract

(57) Abstract: Provided is a hollow fiber for gas separation using a cross-linked modified polyimide membrane. SOLUTION: The hollow fiber comprises a first layer substantially containing a polyimide and a second layer substantially containing a polymer which is not substantially affected by a chemical modification method, wherein the polyimide layer is Contacted with polyamine.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the chemical modification of polyimide films. In particular, the invention relates to the chemical modification of polyimide membranes forming one layer (preferably the outer layer) of a bilayer hollow fiber.

[0002]

Polyimides are attractive gas separation membrane materials because of their good gas separation and physical properties. Much research including tailoring the chemical structure and carrying out cross-linking modification by various methods such as heat treatment, chemical treatment and UV irradiation in order to obtain a polyimide membrane with better gas separation properties Has been implemented. Among all these efforts, cross-linking modification can impart anti-plasticization property to the polyimide film and improve chemical resistance, so it is the most promising to obtain a better film that can be used in complicated and harsh environments. Expected to be a method. Many commercial membranes are in the form of hollow fibers due to their high specific surface area. Each hollow fiber membrane usually contains a thin, dense selective layer and a porous support, and the cross-section morphology is asymmetric.
Is. The asymmetric morphology offers the advantage of high flux needed in practical application of such membranes. US Pat. No. 5,085,676 discloses a method of preparing a two-layer hollow fiber gas separation membrane consisting of a thin selective layer (usually the outer layer) and a porous support (usually the inner layer). Not only do these bilayer membranes have the same high flowability advantages as other asymmetric membranes, but they also optimize material performance and reduce material cost.

However, many polyimides contain C
It is plasticized or chemically attacked by the sorption of O ₂ , H ₂ S or other chemicals. Almost all of the cross-linking modifications of the polyimide carried out to increase chemical resistance and anti-plasticization are carried out on thick, flat, high density films,
The applications for modification of hollow fiber membranes are very limited. For example, US Pat. No. 4,717,393 provides a photochemical method for cross-linking modification of certain polyimides containing hydrogen donor groups such as benzophenone groups and methyl groups. Although this method provides crosslinked polyimides with high gas selective permeability, these crosslinked polyimides have very low gas permeability. U.S. Pat. No. 4,981,497 describes a method of modifying a polyimide film with an amino compound. This modification reduces the gas permeation rate compared to uncrosslinked membranes, but is limited to thick, high density polyimide films and requires heat treatment to complete the reaction. U.S. Pat.No. 4,931,182 discloses certain polyimides containing copolymerizable surface modified units, including both aromatic diamines and alkenylated diamines, where the vinyl or vinyl aryl groups are preferably located in the ortho position of the amine functionality. Membranes are disclosed. When this polyimide film is crosslinked by being treated with an activating force such as irradiation of high-energy electromagnetic waves or a radical source, the magnetic permeability of the composite material is greatly reduced, and the film has high selectivity. Unfortunately, hollow fibers made from these types of polyimides cannot be easily fabricated.

[0004]

Therefore, it is essential to study new and practical cross-linking modification techniques for polyimide membranes, especially for the purpose of finding suitable methods for the production of hollow fibers.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention provides
A method of chemically modifying a two-layer hollow fiber, wherein the fiber comprises a first layer substantially comprising a polyimide and a second substantially comprising a polymer substantially unaffected by the chemical modification process. A layer is provided, the method comprising contacting the polyimide layer with a polyamine. The term "polyimide" as used herein includes blends of two or more polyimides. As used herein, the term "polymer" includes copolymers and blends of two or more polymers and / or copolymers. As used herein, the term "substantially immune to chemical modification" when used to limit the type of polymer is suitable for use as a backing layer for the polyimide. Means that the physical and / or chemical properties of the polymer remain unaffected by the chemical modification process and are only affected to the extent that they do not significantly affect the performance of the polyimide as a support layer. .

In a preferred embodiment, the polyimide forms the outer layer of the bilayer hollow fiber and the polymer, which is substantially unaffected by chemical modification, forms the inner layer of the bilayer hollow fiber. In one embodiment of the invention, the polyamine may be contacted with only one side of the polyimide layer. Preferably, the polyimide layer is contacted with the polyamine at a temperature of 5 to 50 ° C, more preferably 15 to 30 ° C. In one embodiment of the invention, the polyamine is contacted with the polyimide layer in the form of a solution in a suitable solvent. In this case, the contacting is carried out simply by immersing the double-layer hollow fiber in the solution. If a solution of polyamine is used, the polyimide layer is preferably contacted with the polyamine solution and then washed with a solvent. Preferred solvents include water and alcohols that are liquid at ambient temperature, such as methanol. Methanol is particularly preferred.

In a preferred embodiment, at the end of the process the bilayer hollow fiber is 5 to 80 ° C., more preferably 15
Dry at a temperature of ~ 40 ° C. Although the method of the present invention is applicable to many types of polyimides, the preferred polyimide suitable for use in the polyimide layer is an aromatic polyimide film. Preferably, the polyimide layer comprises substantially the following structural units.

[0008]

[Chemical 11] (Wherein each of the n Ar ₁ groups is a tetravalent aromatic moiety independently selected from the group consisting of:

[0009]

[Chemical 12]

And each of the n Ar ₂ groups is a divalent aromatic moiety independently selected from the group consisting of:

[0011]

[Chemical 13]

Z in the formula is selected from the group consisting of:

[0013]

[Chemical 14]

In addition, X, X ₁ , X ₂ and X ₃ in the formula are each independently selected from hydrogen, C _1-5 alkyl, C _1-5 alkoxy, phenyl or phenoxy. )

The value of n must be sufficient to provide a possible polymeric membrane for use as the polyimide layer of the two layer hollow fiber. Preferably, n is a number sufficient to have an intrinsic viscosity of 0.3 dL / g or higher measured at 25 ° C. with respect to a 0.5% by mass solution of the polymer in N-methylpyrrolidone. In a preferred embodiment of the invention, the polyamine is an aliphatic-aromatic polyamine. More preferably, the polyamine is an aliphatic-aromatic diamine. Even more preferably, the polyamine is an aliphatic-aromatic diamine having the following general structure: _{H 2 N (CH 2) a} -Ar 2 - (CH 2) b NH 2 ( wherein, Ar ₂ is as defined above, a and b are each independently selected from 1 to 6. ) Even more preferably, the polyamine is an aliphatic-aromatic diamine having the following general structure:

[0016]

[Chemical 15]

Most preferably, the polyamine is selected from m-xylenediamine or p-xylenediamine. As mentioned above, the polyamine may be used in the form of a solution. In a preferred embodiment of the method, the polyamine is contacted with the polyimide layer in the form of a solution containing 2 to 50% by weight of polyamine, based on the total weight of the solution. More preferably,
The polyimide layer is contacted in the form of a solution containing 2 to 20% by weight of polyamine, based on the total weight of the solution. Most preferably, it is contacted with the polyimide layer in the form of a solution containing 5 to 10% by weight of polyamine, based on the total weight of the solution. The identity of the inert (or non-crosslinked) layer is not critical to the invention. It is merely necessary that it is substantially unaffected by the modification method. Suitable polymers for forming the inert layer may be selected from polyesters, polysulfones, polycarbonates, polyetherketones, polyetheretherketones, polyethersulfones, polyetherimides, polyacrylonitriles, polyamides and polyolefins. Polyether sulfone and polysulfone are particularly preferred.

The present invention also provides the chemically modified two-layer hollow fiber obtained by the above-mentioned method. The present invention is also a method of separating one or more gases from a mixture of two or more gases, which method comprises contacting a pressurized mixture of said gases with a bilayer hollow fiber obtained by the above method. I will provide a. The gas mixture for separation is He and
N ₂ , H ₂ and N ₂ , O ₂ and N ₂ , CO ₂ and CH ₄ , CO ₂ and H ₂ S and
CH ₄ and CO ₂ and H ₂ S and mixtures of CH ₄ and C ₂ -C ₄ hydrocarbons. The two-layer hollow fiber obtained by the above method is a mixture of CO ₂ and CH ₄ or CO ₂ and H ₂ S and CH 4.
Particularly useful for separating a mixture of ₄ . In another aspect, the present invention also provides a method of chemically modifying a polyimide film, comprising contacting the film with an alcoholic solution of an aliphatic-aromatic polyamine. Suitable alcohols for use as a solvent include any alcohol that is liquid at ambient temperature and capable of solubilizing the aliphatic-aromatic polyamines. Methanol is a particularly preferred solvent.

Preferably, the membrane is contacted with the solution at a temperature of 5 to 50 ° C, more preferably 15 to 30 ° C. In a preferred embodiment of the method, the membrane is contacted with the solution and then washed with an alcohol solvent. In another preferred embodiment of the method, after contacting with the solution or washing with an alcohol solvent, the membrane is dried at a temperature of 5 to 80 ° C, more preferably 15 to 40 ° C. In a preferred embodiment of the method, the polyimide film is an aromatic polyimide film. More preferably, the polyimide film substantially contains the following structural units.

[0020]

[Chemical 16] (Wherein each of the n Ar ₁ groups is a tetravalent aromatic moiety independently selected from the group consisting of:

[0021]

[Chemical 17]

And each of the n Ar ₂ groups is a divalent aromatic moiety independently selected from the group consisting of:

[0023]

[Chemical 18]

Where Z is selected from the group consisting of:

[0025]

[Chemical 19]

And, in the formula, X, X ₁ , X ₂ and X ₃ are each independently selected from hydrogen, C _1-5 alkyl, C _1-5 alkoxy, phenyl or phenoxy. )

The value of n must be sufficient to provide a possible polymer film. Preferably n is 2 with respect to a 0.5% by weight solution of the polymer in N-methylpyrrolidone.
The number is sufficient so that the intrinsic viscosity measured at 5 ° C. is 0.3 dL / g or more. In a preferred embodiment of the method,
Aliphatic-aromatic polyamines are aliphatic-aromatic diamines. More preferably, the aliphatic-aromatic polyamine is an aliphatic-aromatic diamine having the following general structure. _{H 2 N (CH 2) a} -Ar 2 - (CH 2) b NH 2 ( wherein, Ar ₂ is as defined above, a and b are each independently selected from 1 to 6. ) Even more preferably, the aliphatic-aromatic polyamine is an aliphatic-aromatic diamine having the following general structure:

[0028]

[Chemical 20]

Most preferably, the aliphatic-aromatic polyamine is selected from m-xylenediamine or p-xylenediamine. Preferably, the aliphatic-aromatic polyamine is present in the form of a solution at a concentration of 2 to 50% by weight, based on the total weight of the solution. More preferably, the aliphatic-aromatic polyamine is present in solution in a concentration of 2 to 20% by weight, based on the total weight of the solution. Most preferably, aliphatic-
The aromatic polyamine is 5 to 10 relative to the total mass of the solution.
It exists in the form of a solution at a concentration of% by weight. In a preferred embodiment, the polyimide membrane is in the form of hollow fibers. In a particularly preferred embodiment, the polyimide membrane is a selective layer of bilayer hollow fibers and the support layer of said bilayer hollow fibers comprises a polymer that is substantially unaffected by chemical modification. Most preferably, the polyimide membrane forms the outer layer of the bilayer hollow fiber. The novelty of the present invention is that polyimide, especially rigid aliphatic such as p-xylenediamine as a chemical cross-linking agent for double-layer hollow fibers using polyimide as the selective layer.
Aromatic diamine alcohol (preferably methanol)
To use the solution.

The modification is advantageously carried out at ambient temperature, and the use of an inert material as the support layer for the two-layer hollow fiber membranes has the side effect of chemical modification, which is often unsuitable for application to two-layer hollow fibers. Help to lower. The present invention provides a method suitable for producing a highly selective and anti-plasticizing two-layer hollow fiber for gas separation, as well as a polyimide (single layer hollow fiber for gas separation In the form or in the form of double-layer hollow fibers). The method of the present invention can produce highly selective and antiplasticizing single phase and bilayer hollow fibers comprising chemically crosslinked polyimide layers for gas separation. To a mixture of gas includes a mixture of _{H 2 / N 2, CO 2} / CH 4 and O ₂ / N _2. The produced membrane can also be used for the separation of volatile organic mixtures.

[0031]

EXAMPLES Comparative Example 1 A stoichiometric amount of 2,2'-bis (3,4-carboxyphenyl) hexafluoropropane dianhydride (6FDA) was stirred under argon atmosphere at ambient temperature for 2,3, 5,6-Tetramethyl-1,4-phenylenediamine (zurendiamine) and 1,3
-Phenylenediamine (mPDA) N-methylpyrrolidone (N
MP) (The molar ratio of zlendiamine to mPDA is 50: 5.
Was 0) solution. After 24 hours, a mixture of acetic anhydride and triethylamine (the molar ratio of acetic anhydride / triethylamine to 6FDA was 4: 1) was slowly added to the solution and imidization was completed in 24 hours.
The polymer slowly precipitated in methanol. After filtration and washing with fresh methanol, the polymer obtained was dried in vacuum at 150 ° C. for 24 hours. The intrinsic viscosity measured in NMP was 1.00 dL / g.

Comparative Example 2 Spinning of a two-layer hollow fiber was carried out as follows. 6FDA- as a dope to form a dense outer selective layer
A 26% by mass NMP / THF (mass ratio 5: 3) solvent mixture solution of zulene / mPDA (50:50) was selected and 28 of polyether sulfone (PES) was used as a dope for forming the inner porous support layer. A mass% NMP / H ₂ O (mass ratio 10: 1) solvent mixture solution was selected. The two dopes were extruded from the spinneret with two metering pumps at a rate of 0.2 ml / min for the outer layer and 0.6 ml / min for the inner layer, respectively. The temperature of the spinneret was controlled at 60 ° C.
NMP / H ₂ O mixed solvent with a mass ratio of 95: 5 was selected as the fluid in the pores, and 0.2 ml /
Released at a rate of minutes. After passing through a 0.3 cm air gap, the hollow fibers produced were transferred to the tap water coagulation layer at ambient temperature and collected at a winding speed of 40 cm / min. After storage in water at room temperature for 3 days, the two-layer hollow fiber was immersed in methanol three times and then in hexane three times for solvent exchange. 3 new solvent for each solvent exchange
Used for 0 minutes. Heat treatment of the hollow fibers was then carried out in vacuum, gradually at 35 ° C., 45 ° C., 55 ° C., 65 ° C. for 30 minutes each and finally at 75 ° C. for 1 hour.

The SEM micrograph of the bilayer asymmetric hollow fiber is shown in FIG.
Is shown in. For the SEM experiment, the double-layer hollow fiber was immersed in liquid nitrogen, crushed, and sputtered with gold using a JEOL JFC-1100E ion sputter device. Philips XL30-SEM was used for the study of fiber morphology. The two-layer hollow fiber has good concentricity with a hollow inner diameter of 170 μm. FIG. 1 shows the asymmetric morphology of the outer layer containing a thin, dense selective layer near the outer surface. The thickness of the outer polyimide layer and the inner PES porous layer are 10 and 100 μm, respectively. No delamination is observed between the outer and inner layers. The inner layer contains porous, continuous, large voids so that the substructure resistance to gas transport can be significantly minimized. As a result, the outer polyimide layer determines the gas separation performance of the two-layer hollow fiber. 10 lengths 2
An epoxy resin (Araldite®, Switzerlan®) that rapidly solidifies one of the ends of a 0 cm bundle of hollow fibers in 5 minutes.
d) Seal the other end with a hardener 105 (Changsha
Institute of Chemical Engineering, Changsha, P.
R.China) cured epoxy resin H-711 (Tian
jin Jindong Chemical Plant, Tianjin, PR China)
5 by sticking it on an aluminum holder with
Individual modules were prepared.

O₂And CH_FourPermeation rate of 13.8 bar
(200 psi), N₂And CO ₂Is 3.4 to 3
Performed in the pressure range of 4.5 bar (50 to 500 psi)
did. All measurements were performed at 24 ° C. Gaseous
Permeability and separation rate were measured using a bubble flow meter and reported.
(Based on cellulose nitrate by J. J. Shieh, T. S. Chung
Multilayer composite membranes for cell-based gas separation (Cellulose
nitrate-based multilayer composite membranes for g
As separation) (J. Membr. Sci., 66 (20
00) 259)).
Table 1 shows the gas permeability of the module immediately after manufacturing.

[0035]

[Table 1] Table 1 Gas separation characteristics of polyimide-polyether sulfone two-layer hollow fiber module immediately after spinning ^{a a} Measured at 24 ° C. For CO ₂ and other gases, the supply pressure is 6.9 to 13.8 bar (1
00 and 200 psi). ^b 1 GPU = 1 × 10 ^-6 cm ³ (STP) / cm ² · sec · cmHg

Comparative Example 1 and Examples 2-5 Chemical cross-linking modification of the modules was carried out 5 days after the CO ₂ permeation test in order to eliminate the plasticizing effect of CO ₂ during and after the permeation measurements. Using Module 1 as a control, Modules 2, 3, 4 and 5 were immersed in 5% (mass / volume) p-xylenediamine methanol solution for 0.5, 1, 3 and 5 minutes respectively. ATR-FTIR measurements were performed using a Perkin Elmer FTIR spectrometer with careful flattening of the hollow fibers. FIG. 2 shows a comparison of the FTIR spectra of the polyimide outer layer of the two-layer hollow fiber before and after cross-linking modification. Figure 2b
Or as shown in 2e, after denaturation characteristic peaks of amide groups at 1660 cm ^-1 and 1539cm ^-1 (respectively, asymmetric stretching and symmetric stretching of C = O in amide group)
Was observed. As the chemical modification progresses, as the immersion time increases, 1786 cm ^-1 (C = O asymmetric expansion and contraction in the imide group), 1713 cm ^-1 (C = O symmetric expansion and contraction in the imide group) and 1350 cm ^-1 (imide The intensity of the characteristic peak of the imide group in (stretching of CN in the group) decreased.
These phenomena indicate that the reaction between the p-xylenediamine and imide groups produces amide groups and chemical crosslinks are formed.

FIG. 3 shows a comparison of the FTIR spectra of the polyethersulfone inner layer of unmodified and modified bilayer hollow fibers after careful removal of the polyimide outer layer. No obvious changes in the chemical structure of the PES inner layer can be detected in Figure 3b as compared to Figure 3a. Apparently, the PES inner layer is inert to the proposed chemical cross-linking modification. The modified sample contains 5% hollow fiber (mass / volume)
Obtained by immersing in p-xylenediamine methanol solution for 16 hours. However, Figures 2a to 2e
The chemical modification resulted in a significant change in the chemical structure of the polyimide outer layer, as shown in the comparison in FIG. The inertness of the PES inner layer ensures that the chemical cross-linking modification does not have a significant adverse effect on the support layer. For example, with respect to mechanical properties, the crosslinked bilayer hollow fibers obtained by soaking in a 5% (mass / volume) p-xylenediamine methanol solution for 16 hours remain flexible, but for 1 hour. Single layer 6FDA-dulene / mPDA even by immersion
(50:50) Hollow fibers become brittle.

Table 2 shows modules 1a, 2c, 3c and 4
Control module and cross-linking modified module corresponding to c and 5c
The gas separation characteristics of the tool are shown. Bilayer membrane uses phase inversion technology
The precipitation process is non-equilibrium. Single layer
Hollow hollow fiber membrane [W. J. Koros, G. K. Fleming, Membrane-
based gas separation, J. Membr. Sci., 83 (1993) 1;
S. A. Stern, Polymers for the gas separation: the
next decade, J. Membr. Sci., 94 (1994) 1; T. S. Ch
ung, S. K. Teoh, The ageing phenomenon of polyethe
rsulfone hollow fiber membranes for gas separation
 and their characteristics, J. Membr. Sci., 152 (1
999) 175], the performance of the bilayer film immediately after spinning is
It drops sharply in 40 days and then becomes constant. This aging
Phenomena tend to relax and compress towards equilibrium
Is a typical property of glass polymers. By compression,
The free volume and gaps between polymer chains that are effective for gas permeation
Decrease. Therefore, comparing Tables 1 and 2, a few days
Aging (CO after permeation measurement ₂5 days to remove the effect
And after 2 days for cross-linking modification)
It shows that the permeability is significantly reduced.

[0039]

TABLE 2 Control and crosslinked polyimide - gas separation properties of a polyether sulfone bilayer hollow fiber module ^{a a} Measured at 23 ° C. O ₂ and N ₂ supply pressure is 13.8
It was 200 bar and that of CO ₂ was 6.9 bar (100 psi). ^b 1 GPU = 1 × 10 ^-6 cm ³ (STP) / cm ² · sec · cmHg

Crosslinking modules 2c, 3 shown in Table 2
c, 4c and 5c and the control module 1a show that cross-linking the double-layer hollow fiber reduces the gas permeation rate, especially CO 2
It is clearly shown that the gas separation rate increases in ₂ / CH ₄ . Furthermore, the gas permeation rate decreases as the immersion time increases. Figure 4 and 5 was measured at 23 ° C. at a pressure range of 3.4 to 34.5 bar (50 to 500 psi), a gas capable N _2, and then relatively compressed a gas that can not be relatively compressed CO ₂ shows the gas permeation rate of ₂ .

Since the polyimide / PES bilayer hollow fibers are not plasticized by N ₂ absorption, the experimental results shown in FIG. 4 show that the N ₂ permeation of the bilayer hollow fibers decreases with increasing feed pressure. Indicates. This relationship is consistent with the partially fixed two-layer model. The Langmuir site saturates quickly and contributes little to the total diffusivity. On the other hand, in FIG. 5, the CO ₂ permeation of the two-layer hollow fiber is
It is shown to increase with increasing feed pressure in the total pressure range of 3.4 to 34.5 bar (50 to 500 psi). This phenomenon occurs due to increased free volume and polymer chain mobility due to plasticization by absorption of CO ₂ which can be compressed. The increasing tendency of gas permeability when the feed pressure is higher than the plasticizing pressure has been extensively studied for thick polymeric high density films. However, thick dense films and bilayer fibers have different degrees of CO ₂ plasticization. Figure 5
CO ₂ permeation of unmodified two-layer hollow fiber, module 1a
It is shown to increase with increasing pressure in the total measuring range starting from 3.4 bar (50 psi) and approximately 4.1 times when the feed pressure reaches 34.5 bar (500 psi). Under similar conditions, similar structure thickness 20
In the case of mm high-density polyimide film, it is about doubled [MJ Thundyil, YH Jois, WJ Koros, Eff
ect of permeate pressure on the mixed gas permeati
on of carbon dioxide and methane in a glassy polyi
mides, J. Membr. Sci., 152 (1999) 29]. The large increase in permeability is due to the fact that the bilayer hollow fibers initiate plasticization at low feed pressures, indicating that the thin asymmetric polyimide outer layer is more susceptible to plasticization than the thick high density film. Show. A similar phenomenon was observed by Professor Koros's research group who reported that the plasticization of single-layer asymmetric hollow fibers was greater than that of thick, flat, dense films [SM Jordan, MA Henson, WJ Koros, Th.
e effect of carbon dioxide conditioning on the per
meation behavior of hollow fiber asymmetric membran
es, J. Membr, Sci., 54 (1990) 103]. The easier plasticization of asymmetric hollow fibers is probably due to the fact that they are loosely packed nodules with a thin, dense selective layer of hollow fibers. Therefore, they can easily swell on absorption of CO ₂ .

FIG. 5 shows that the proposed chemical cross-linking modification was CO ₂
It is shown that it is effective in suppressing the plasticization of the double-layer hollow fiber induced by. The cross-linked two-layer hollow fibers, modules 2c, 3c, 4c, and 5c, have a significantly reduced increase in permeability with increasing feed pressure compared to the unmodified module 1a. Furthermore, if the degree of cross-linking is increased by soaking for a longer time, the plasticization tendency is reduced. The improvement in anti-plasticity reduces CO ₂ sorption and prevents the nodules from swelling, mainly because the proposed cross-linking modifications stiffen and strengthen the polyimide nodules. As a result, united resistance and its effective thickness of the outer thin dense selective layer, sensitivity decreases relative to CO ₂ sorption after chemical modification.

[Brief description of drawings]

FIG. 1 shows a scanning electron microscope (SEM) photograph of a cross section of a polyimide / polyether sulfone (PES) bilayer hollow fiber membrane.

FIG. 2 shows a typical FTIR spectrum of the outer layer of unmodified and crosslinked bilayer hollow fibers.

FIG. 3: FTI of PES inner layer of unmodified and cross-linked bilayer hollow fibers
The R spectrum is shown.

FIG. 4 shows the effect of feed pressure on N ₂ permeability of unmodified and crosslinked polyimide / PES bilayer hollow fibers.

FIG. 5 shows the effect of feed pressure on the CO ₂ permeability of unmodified and crosslinked polyimide / PES bilayer hollow fibers.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08J 7/00 CFG C08J 7/00 CFGA // C08L 79:08 C08L 79:08 Z D06M 101: 36 D06M 101 : 36 (72) Inventor Yeliu Singapore Clementi Ave 4 Block 304 # 03-499 (72) Inventor Don Feili Singapore West Ave 6 Bukit Buttock Block 130 # 08-360 (72) Inventor Rong One Singapore # 01- 08 West Coast Crescent 56 (72) Inventor Thai Shun Chun Singapore Clementi Road Block 103 # 08-02 F Term (Reference) 4D006 GA41 HA02 JA02A JA02C JA13A JA13C JB06 MA01 MA06 MA33 MB04 MC58 MC58X MC62 MC62X MC78 MC78X NA54 NA64. UB132 UB151 UB152 UB301 UB302 VA041 VA081 YB32 ZB04 ZB15 ZB58 4L033 AA08 AC15 BA11 CA57

Claims (44)

[Claims] 1. A method of chemically modifying a two-layer hollow fiber, wherein the fiber comprises a first layer substantially comprising polyimide and a polymer substantially free from chemical modification. A second layer comprising: contacting the polyimide layer with a polyamine. 2. The polyimide forms the outer layer of the two-layer hollow fiber, and the polymer substantially unaffected by the chemical modification method forms the inner layer of the two-layer hollow fiber. The method described in 1. 3. The method of claim 1 or 2 wherein the polyamine is contacted with only one side of the polyimide layer. 4. The method according to claim 1, wherein the polyimide layer is contacted with the polyamine at a temperature of 5 to 50 ° C. 5. The method according to claim 1, wherein the polyimide layer is contacted with the polyamine at a temperature of 15 to 30 ° C. 6. A method according to claim 1, wherein the polyamine is in the form of a solution of a solvent suitable for contacting with the polyimide layer. 7. The method of claim 6, wherein the polyimide layer is washed with a solvent after contact with the polyamine solution. 8. At the end of the method, the two-layer hollow fiber is treated with 5
The method according to any one of claims 1 to 7, which is dried at a temperature of from 80 to 80 ° C. 9. At the end of the method, the two-layer hollow fiber is
The method according to any one of claims 1 to 8, which is dried at a temperature of 5 to 40 ° C. 10. The method according to claim 1, wherein the polyimide layer is an aromatic polyimide film. 11. The method according to claim 1, wherein the polyimide layer comprises substantially the following structural units. [Chemical 1] (Wherein each of the n Ar ₁ groups is a tetravalent aromatic moiety independently selected from the group consisting of: And each of the n Ar ₂ groups is a divalent aromatic moiety independently selected from the group consisting of: Z in the formula is selected from the group consisting of: And, in the formula, X, X ₁ , X ₂ and X ₃ are each independently hydrogen, C
It is selected from _1-5 alkyl, C _1-5 alkoxy, phenyl or phenoxy. ) 12. The n is a number sufficient to have an intrinsic viscosity of 0.3 dL / g or more measured at 25 ° C. with respect to a 0.5% by mass N-methylpyrrolidone solution of the polymer. the method of. 13. The method according to claim 1, wherein the polyamine is an aliphatic-aromatic polyamine. 14. The method according to claim 1, wherein the polyamine is an aliphatic-aromatic diamine. 15. The method according to claim 1, wherein the polyamine is an aliphatic-aromatic diamine having the following general structure. H ₂ N (CH ₂ ) _a -Ar _2- (CH ₂ ) _b NH ₂ (wherein Ar ₂ is as described in claim 11, and a and b
Are each independently selected from 1 to 6. ) 16. The method according to claim 1, wherein the polyamine is an aliphatic-aromatic diamine having the following general structure. [Chemical 5] 17. The method according to claim 1, wherein the polyamine is selected from m-xylenediamine or p-xylenediamine. 18. The method according to claim 1, wherein the polyamine is contacted with the polyimide layer in the form of a solution containing 2 to 50% by weight of polyamine with respect to the total weight of the solution. 19. The method according to claim 1, wherein the polyamine is contacted with the polyimide layer in the form of a solution containing 2 to 20% by weight of polyamine, based on the total weight of the solution. 20. The method according to claim 1, wherein the polyamine is contacted with the polyimide layer in the form of a solution containing 5 to 10% by weight of polyamine, based on the total weight of the solution. 21. A chemically modified two-layer hollow fiber obtained by the method according to any one of claims 1 to 20. 22. A method of separating one or more gases from a mixture of two or more gases, which method comprises contacting a pressurized mixture of the gases with the bilayer hollow fiber of claim 21. 23. The gas mixture for separation is He and
N ₂ , H ₂ and N ₂ , O ₂ and N ₂ , CO ₂ and CH ₄ , CO ₂ and H ₂ S and
CH _4, and CO ₂ and H ₂ S and CH ₄ and C ₂ -C ₄ The method of claim 22, wherein the mixtures of the hydrocarbons. 24. The gas mixture for separation is CO
₂ and CH _4, and a method of claim 22, wherein the mixtures of the CO ₂ and H ₂ S and CH _4. 25. A method of chemically modifying a polyimide film comprising contacting the film with an alcoholic solution of an aliphatic-aromatic polyamine. 26. The method of claim 25, wherein the alcoholic solution of the aliphatic-aromatic polyamine is a methanolic solution of the aliphatic-aromatic polyamine. 27. The method according to claim 25 or 26, wherein the membrane is contacted with the solution at a temperature of 5 to 50 ° C. 28. The method according to claim 25, wherein the membrane is contacted with the solution at a temperature of 15 to 30 ° C. 29. The method according to claim 25, wherein the membrane is contacted with the solution and then washed with an alcohol solvent. 30. The method according to claim 25, wherein the membrane is dried at a temperature of 5 to 80 ° C. after being brought into contact with the solution or washed with the alcohol solvent. 31. The method of claim 30, wherein the film is dried at a temperature of 15-40 ° C. 32. The method according to claim 25, wherein the polyimide film is an aromatic polyimide film. 33. The method according to claim 25, wherein the polyimide film substantially comprises the following structural units. [Chemical 6] (Wherein each of the n Ar ₁ groups is a tetravalent aromatic moiety independently selected from the group consisting of: And each of the n Ar ₂ groups is a divalent aromatic moiety independently selected from the group consisting of: Z in the formula is selected from the group consisting of: And, in the formula, X, X ₁ , X ₂ and X ₃ are each independently hydrogen, C
It is selected from _1-5 alkyl, C _1-5 alkoxy, phenyl or phenoxy. ) 34. The n is a number sufficient to have an intrinsic viscosity of 0.3 dL / g or more measured at 25 ° C. with respect to a 0.5% by mass solution of the polymer in N-methylpyrrolidone. the method of. 35. The method according to any one of claims 25 to 34, wherein the aliphatic-aromatic polyamine is an aliphatic-aromatic diamine. 36. The method according to claim 25, wherein the aliphatic-aromatic polyamine is an aliphatic-aromatic diamine having the following general structure. _{H 2 N (CH 2) a} -Ar 2 - (CH 2) b NH 2 ( wherein, Ar ₂ is as defined above, a and b are each independently selected from 1 to 6. ) 37. The method according to any one of claims 25 to 36, wherein the aliphatic-aromatic polyamine is an aliphatic-aromatic diamine having the following general structure. [Chemical 10] 38. The method according to any one of claims 25 to 37, wherein the aliphatic-aromatic polyamine is selected from m-xylenediamine or p-xylenediamine. 39. The method according to claim 25, wherein the aliphatic-aromatic polyamine is present in the solution in a concentration of 2 to 50% by weight, based on the total weight of the solution. 40. The method according to claim 25, wherein the aliphatic-aromatic polyamine is present in the solution in a concentration of 2 to 20% by weight, based on the total weight of the solution. 41. The method according to claim 25, wherein the aliphatic-aromatic polyamine is present in the solution in a concentration of 5 to 10% by weight, based on the total weight of the solution. 42. The method according to claim 25, wherein the polyimide membrane is in the form of hollow fibers. 43. The polyimide membrane is an outer layer of a two-layer hollow fiber, and the inner layer of the two-layer hollow fiber comprises a polymer that is substantially unaffected by chemical modification.
The method according to any of 5 to 41. 44. The polyimide membrane is an inner layer of a two-layer hollow fiber, and the outer layer of the two-layer hollow fiber contains a polymer that is substantially unaffected by chemical modification.
The method according to any of 5 to 41.